The prosthetic impingement occurs if the range of motion of the hip exceeds implant mobility or in case of component malorientation. This retrieval study was designed to assess the frequency and the risk factors of this phenomenon. The frequency and the severity of the impingement were calculated from a continuous series of 311 cups retrievals collected between 1989 and 2004 by a single surgeon. The reason for retrieval was loosening (131 cases), infection (43 cases), instability (56 cases), osteolysis (28 cases), unexplained pain (48 cases) and prosthetic impingent (5 cases all with hard bearings). The notching at the cup rim was assessed twice by two examiners with optic magnification. The risk factors were analyzed from clinical charts by univariate and cox multihazard.Introduction
Material and Methods
Implantation of a large-diameter femoral head prosthesis with a metal-on-metal bearing surface reduces the risk of dislocation, increases the range of movement, minimises the risk of impingement and, in theory, results in little wear. Between February 2004 and March 2007 we implanted 100 consecutive total hip replacements with a metal-on-metal bearing and a large femoral head into 92 patients. There were 51 men and 41 women with a mean age of 50 years (18 to 70) at the time of surgery. Outcome was assessed using the Western Ontario McMaster University osteoarthritis index and the Harris hip score as well as the Devane activity score. These all improved significantly (p <
0.0001). At the last follow-up there were no cases of dislocation, no impingement, a good range of movement and no osteolysis, but seven revisions, two for infection and five for aseptic loosening. The probability of groin pain increased if the other acetabular component inclination exceeded 50° (p = 0.0007). At 4.8 years of follow-up, the projected survival of the Durom acetabular component, with revision for any reason, was 92.4% ( The design of the component made it difficult both to orientate and seat, which when combined with a poor porous coating, produced unpredictable fixation and a low survival at five years.